This quantum dot spectrometer fits on your smartphone

A portable spectrometer small enough to fit inside a smartphone camera could soon be used to diagnose diseases including skin cancer.

As well as diagnosing diseases the portable spectrometer could also be used to analyse urine samples, check pulse and oxygen levels and measure environmental pollutants.

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The research, conducted at Massachusetts Institute of Technology (MIT) could also have applications in space, with spectrometers widely used on missions exploring our solar system and beyond. Further details were published in the journal Nature. "Using quantum dots for spectrometers is such a straightforward application compared to everything else that we've tried to do, and I think that's very appealing," said Moungi Bawendi, professor of chemistry at MIT and senior author of the research.

Spectrometers, which separate light into its constituent wavelengths, are used to study everything from atomic processes to tissue samples. As all elements have a specific light signature spectrometers are able to identity the makeup of everything in the universe.

Modern spectrometers work by diffracting light before sending it through a sensor to see exactly what wavelengths are being let through. Shrinking spectrometers down is both expensive and technically challenging, with the high-precision equipment difficult to manufacture on small scales.

Quantum dots, discovered in the early 1980s, are made by combining metals with other elements to create tiny dots with different electronic properties. The remarkable light absorption properties of the dots make them an ideal fit for spectrometers, the team at MIT explained.

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The new quantum dot spectrometer uses hundreds of different dots that each filter specific wavelengths of light. As each dot only lets through a certain wavelength of light it can carry out the same task as a far larger, clunkier spectrometer. The dots are so small they can be printed onto a thin film and can be placed on top of a smartphone camera.

In their experiments researchers used 200 types of quantum dots spread over 300 nanometers. Higher resolution results could be achieved by increasing the number of dots, they said.

As well as being smaller and easier to produce the researchers also said quantum dots could be manufactured cheaply, dramatically undercutting the cost of a standard spectrometer.